1. Field of the Invention
The present invention relates to a resist composition used for fine processing of semiconductors.
2. Prior Art
In general, a photolithography process is used for producing integrated circuits and liquid crystal display elements. It is known that as the resist used in such a process, compositions containing a novolak resin and a dissolution inhibiting agent having a quinone diazide group are suitable, and such compositions are used widely in lithography using g line, i line and the like. However, even these resists revealed a necessity for improvement in close adherence in a wet etching process and heat resistance in a plasma etching process, for precise formation of fine patterns.
Recently, with progress in higher integration, there occurs a requirement for capability of precise formation of submicron fine patterns. Excimer laser lithography is paid to attention since it enables production of 64 M DRAM to 1 G DRAM. As the resist suitable for such an excimer laser lithography process, there is a tendency to adoption of a so-called chemical amplification type resist utilizing chemical amplification effect of an acid catalyst. In the case of the chemical amplification type resist, an acid is generated from an acid generating agent at parts irradiated with radiation, and solubility of the irradiated parts in an alkali developer is changed in a reaction using this acid as a catalyst, by the subsequent heat treatment (post exposure bake: hereinafter, abbreviated as PEB) in some cases. By this, positive or negative patterns are provided.
These resists are generally a composition showing high transparency at exposure wavelength, since high resolution is required. For example, as the resist for KrF excimer laser lithography, often used are poly(p-hydroxystyene) based resins in which a part of phenolic hydroxyl groups is protected with a group dissociating by the action of an acid. However, when wet etching treatment and the like are conducted using these chemical amplification type resists, there is a problem that peeling of a formed pattern from the edge due to insufficient close adherence at the interface of a substrate with a resist, reverse influence due to impregnation of etching liquid and the like are caused.
The object of the present invention is to provide a resist composition, particularly a positive resist composition giving improved close adherence at the interface of a substrate with a resist, improving the problems in wet etching treatment, and excellent in sensitivity, resolution and heat resistance.
The present inventors have intensively studied, and resultantly found that by containing a specific compound, a resist composition giving improved close adherence at the interface of a substrate with a resist and capable of improving the problems in wet etching treatment is obtained. Based on this findings and further various studies, the present invention was completed.
Namely, the present invention relates to [1] a resist composition comprising a compound of the general formula (I): 
wherein, R1 and R2 represent each independently a hydrogen atom or an alkyl group, R3 represents a hydrogen atom, alkyl group, aryl group, aralkyl group, alkenyl group, alkylcarbonyl group, arylcarbonyl group or aralkylcarbonyl group provided that the alkyl group, aryl group, aralkyl group, alkenyl group, alkylcarbonyl group, arylcarbonyl group and aralkylcarbonyl group may be optionally substituted with a carboxy group, oxycarbonyl group, hydroxy group, alkoxy group or alkyl group, n represents an integer of 1 to 40, m represents an integer of 1 to 5, and l represents an integer of 1 to 5.
Further, the present invention relates to [2] a positive resist composition comprising an alkali-soluble resin, a dissolution inhibiting agent and a compound of the general formula (I).
Furthermore, the present invention relates to [3] a chemical amplification type positive resist composition comprising a resin insoluble or poorly soluble itself in an alkali aqueous solution but becoming soluble in an alkali aqueous solution by the action of an acid, an acid generating agent and a compound of the above-mentioned general formula (I).
The resist composition of the present invention is characterized in that it comprises a compound of the above-mentioned formula (I). The compound of the formula (I) can be used alone or in combination of two or more.
In the formula (I), R1 and R2 represent each independently a hydrogen atom or an alkyl group, preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, further preferably a hydrogen atom or a methyl group.
R3 represents a hydrogen atom, alkyl group, aryl group, aralkyl group, alkenyl group, alkylcarbonyl group, arylcarbonyl group or aralkylcarbonyl group, preferably a hydrogen atom, alkyl group having 1 to 10 carbon atoms, aryl group having 6 to 15 carbon atoms, aralkyl group having 7 to 15 carbon atoms, alkenyl group having 2 to 10 carbon atoms, alkylcarbonyl group having 2 to 10 carbon atoms, arylcarbonyl group having 7 to 15 carbon atoms or aralkylcarbonyl group having 7 to 15 carbon atoms. Among the above, a hydrogen atom, alkylcarbonyl group having 2 to 10 carbon atoms, arylcarbonyl group having 7 to 15 carbon atoms and aralkylcarbonyl group having 7 to 15 carbon atoms are more preferable.
The alkyl group, aryl group, aralkyl group, alkenyl group, alkylcarbonyl group, arylcarbonyl group or aralkylcarbonyl group may be optionally substituted with a carboxy group, oxycarbonyl group, hydroxy group, alkoxy group or alkyl group.
The alkyl group, alkenyl group include straight chain, branched and cyclic groups.
As R3, particularly a group represented by the following formula (II) is preferable. 
n represents an integer of 1 to 40, preferably of 1 to 20. m represents an integer of 1 to 5, and l represents an integer of 1 to 5.
The end of the compound of the formula (I) is a hydrogen atom.
The compound of the general formula (I) preferably has a weight-average molecular weight measured by gel permeation chromatography (GPC) in terms of polystyrene of 500 to 20000.
Specific examples of the compound corresponding to the formula (I) include the following compounds. 
A compound of the formula (I) wherein R3 represents H, such as a compound of the formula (IIIc) is obtained by adding an unsaturated monocarboxylic acid such as acrylic acid, methacrylic acid or the like, according to a known method, to a novolak epoxy resin such as a cresol novolak epoxy resin, phenol novolak epoxy resin or the like. Further, by effecting an addition reaction to the hydroxyl group (esterification) according to a known method, compounds of the formula (I) wherein R3 represents various groups are obtained. For example, if tetrahydrophthalic anhydride is reacted with a novolak epoxy resin, compounds corresponding to the formula (IIIa) and the formula (IIIb) are obtained.
The compounds of the formula (I) are also commercially available, and exemplified are resins manufactured by Showa Kobunshi K.K. (trade name: PR-310), and the like.
The alkali-soluble resin used in the resist composition of the present invention (composition [2]) is not particularly restricted, and those known in the art can be used. Preferably used are novolak resins. The novolak resin is usually obtained by condensation of a phenol-based compound and an aldehyde in the presence of an acid catalyst. Examples of the phenol-based compound used in production of the novolak resins include phenol, o-, m- or p-cresol, 2,3-, 2,5-, 3,4- or 3,5-xylenol, 2,3,5-trimethylphenol, 2-, 3- or 4-tert-butylphenol, 2-tert-butyl-4- or 5-methylphenol, 2-, 4- or 5-methylresorcinol, 2-, 3- or 4-methoxyphenol, 2,3-, 2,5- or 3,5-dimethoxyphenol, 2-methoxyresorcinol, 4-tert-butylcatechol, 2-, 3- or 4-ethylphenol, 2,5- or 3,5-diethylphenol, 2,3,5-triethylphenol, 2-naphthol, 1,3-, 1,5- or 1,7-dihydroxynaphthalene, polyhydroxytriphenylmethane-based compounds obtained by condensation of xylenol and hydroxybenzaldehyde, and the like. These phenol compounds can be used alone or in combination of two or more.
Examples of the aldehyde used in production of the novolak resin include aliphatic aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, n-butylaldehyde, isobutylaldehyde, acrolein or crotonaldehyde; alicyclic aldehydes such as cyclohexanealdehyde, cyclopentanealdehyde, furfural or furylacrolein; aromatic aldehydes such as benzaldehyde, o-, m- or p-methylbenzaldehyde, p-ethylbenzaldehyde, 2,4-, 2,5-, 3,4- or 3,5-dimethylbenzaldehyde or o-, m- or p-hydroxybenzaldehyde; aromatic aliphatic aldehydes such as phenylacetaldehyde or cinnamic aldehyde; and the like. These aldehydes can also be used each alone or in combination of two or more if necessary. Of these aldehydes, formaldehyde is preferably used since it is industrially obtainable easily.
Examples of the acid catalyst used in condensation of a phenol-based compound with an aldehyde include inorganic acids such as hydrochloric acid, sulfuric acid, perchloric acid or phosphoric acid; organic acids such as formic acid, acetic acid, oxalic acid, trichloroacetic acid or p-toluenesulfonic acid; divalent metal salts such as zinc acetate, zinc chloride or magnesium acetate. These acid catalysts can also be used each alone or in combination of two or more. The condensation reaction can be conducted according an ordinary method, for example, conducted at temperatures in the range from 60 to 120xc2x0 C. for about 2 to 30 hours.
Regarding novolak resins obtained by condensation, it is preferable that components of lower molecular weight are removed by performing operations such as fractionation and the like, for narrowing the molecular weight distribution, to give a resin mainly composed of components of higher molecular weights. Specifically, it is preferable that when the novolak resin is measured by gel permeation chromatography (GPC) using polystyrene as a standard, the area ratio of components having molecular weights of 1000 or less is 25% or less, more preferably 20% or less based on the total pattern area excepting unreacted monomers.
The dissolution inhibiting agent in the present invention acts on an alkali-soluble resin for suppressing solution speed. As the dissolution inhibiting agent, quinone diazide compounds, specifically, o-quinone diazide sulfonates of compounds having a phenolic hydroxyl group are usually used. Preferable are 1,2-naphthoquinone diazide-5-sulfonates, 1,2-naphthoquinone diazide-4-sulfonates or 1,2-benzoquinone diazide-4-sulfonates of polyhydroxy compounds having at least three phenolic hydroxyl groups. Such quinone diazide compounds can be used each alone or in combination of two or more. As the compound having a phenolic hydroxyl group to be quinone diazide-sulfonated, for example, tri-, tetra- or penta-hydroxybenzophenones; polynuclear novolak compounds such as tri-nuclear body, tetra-nuclear body, penta-nuclear body and hexa-nuclear body in which two or more phenol nuclei optionally substituted with an alkyl group, specifically, a phenol nucleus, cresol nucleus, xylenol nucleus and the like are bonded in any order via methylene, are listed.
The quinone diazide sulfonate can be produced by reacting the above-mentioned compound having a phenolic hydroxyl group with an o-quinone diazide sulfonic halide in a suitable solvent in the presence of a base such as triethylamine. After reaction, the intended quinone diazide sulfonate can be obtained by suitable post treatment. Exemplified are a method in which a reaction mass is mixed with water to precipitate the intended compound which is filtrated and dried to give an ester in the form of powder, a method in which a resist solvent such as 2-heptanone and the like is added to a reaction mass, the resulted mixture is washed with water and separated, then, the reaction solvent is removed by distillation and equilibrium flash distillation, to obtain an ester in the form of resist solvent solution. The equilibrium flash distillation here referred to is a kind of continuous distillation operation and a distillation method in which a part of a liquid mixture is vaporized, and the generated gas phase is allowed to contact with the liquid phase sufficiently, and a gas is separated from liquid when reached equilibrium. This is suitable for concentration of a heat labile substance since vaporization efficiency is extremely excellent, vaporization occurs almost momentarily, and gas phase and liquid phase reaches immediately to equilibrium condition, consequently, concentration is sufficiently attained even if gas phase and liquid phase are separated immediately, and heating time may be short.
Next, the chemical amplification type positive resist composition of the present invention (composition [3]) is characterized in that it comprises a resin insoluble or poorly soluble itself in an alkali aqueous solution but becoming soluble in an alkali aqueous solution by the action of an acid, an acid generating agent and a compound of the above-mentioned general formula (I). As the resin insoluble or poorly soluble itself in an alkali aqueous solution but becoming soluble in an alkali aqueous solution by the action of an acid in the present invention, resins having a protective group which can be dissociated by the action of an acid are mentioned.
In such a chemical amplification positive resist, an acid generated in parts irradiated with radiation is diffused by the subsequent heat treatment (post exposure bake), by this, protective groups of a resin and the like are dissociated and an acid is regenerated, and the parts irradiated with radiation are made to be alkali-soluble.
As such a resin having a protective group which can be dissociated by the action of an acid, and insoluble or poorly soluble itself in an alkali but becoming alkali-soluble by the action of an acid after dissociation of the above-mentioned protective group, those obtained by introducing a protective group which can be dissociated by the action of an acid into an alkali-soluble resins can be listed. As the alkali-soluble resin, resins having a phenol skeleton and resins having a (meth)acrylic acid skeleton, such as polyvinylphenol resins, polyisopropenylphenol resins, resins obtained by partial alkyl-etherification of hydroxyl groups in these polyvinylphenol resins or polyisopropenylphenol resins, copolymerized resins of vinylphenol or isopropenylphenol with other polymerizable unsaturated compounds are exemplified.
As such a group showing a solution inhibiting ability on an alkali aqueous solution but instable to an acid, groups in which quaternary carbon is bonded to an oxygen atom such as tert-butyl, tert-butoxycarbonyl or tert-butoxycarbonylmethyl; acetal type groups such as tetrahydro-2-pyranyl, tetrahydro-2-furyl, 1-ethoxyethyl, 1-(2-methylpropoxy)ethyl, 1-(2-methoxyethoxy)ethyl, 1-(2-acetoxyethoxy)ethyl, 1-[2-(1-adamantyloxy)ethoxy]ethyl or 1-[2-(1-adamanthanecarbonyloxy)ethoxy]ethyl; residues of non-aromatic cyclic compounds such as 3-oxocyclohexyl, 4-methyltetrahydro-2-pyron-4-yl (derived from mevalonic lactone), 2-methyl-2-adamantyl or 2-ethyl-2-adamantyl, and the like are exemplified.
These groups shall be substituted for hydrogen on a phenolic hydroxyl group or hydrogen on a carboxyl group.
These protective groups can be introduced into an alkali-soluble resin having a phenolic hydroxyl group or a carboxyl group, by a protective group introduction reaction according to a usual esterification reaction. The above-mentioned resin can also be obtained by copolymerization using, as one monomer, an unsaturated compound having such a group.
The acid generating agent in the composition of the present invention include various compounds generating an acid by irradiating the substance itself or a resist composition containing this substance with radiation. As the acid generating agent, for example, onium salts, halogenated alkyltriazine-based compounds, disulfone-based compounds, compounds having a diazomethanesulfonyl skeleton, sulfonate-based compounds and the like are listed. Specific examples of such acid generating agents include the following compounds.
Diphenyliodonium trifluoromethanesulfonate,
4-methoxyphenylphenyliodinium hexafluoroantimonate,
4-methoxyphenylphenyliodinium trifluoromethanesulfonate,
bis(4-tert-butylphenyl)iodonium tetrafluoroborate
bis(4-tert-butylphenyl)iodonium hexafluorophosphate,
bis(4-tert-butylphenyl)iodonium hexafluoroantimonate
bis(4-tert-butylphenyl)iodonium trifluoromethanesulfonate,
triphenylsulfonium hexafluorophosphate,
triphenylsulfonium hexafluoroantimonate,
triphenylsulfonium trifluoromethanesulfonate,
4-methoxyphenyldiphenylsulfonium hexafluoroantimonate,
4-methoxyphenyldiphenylsulfonium trifluoromethanesulfonate,
p-tolyldiphenylsulfonium trifluoromethanesulfonate,
p-tolyldiphenylsulfonium perfluorobutanesulfonate,
p-tolyldiphenylsulfonium perfluorooctanesulfonate,
2,4,6-trimethylphenyldiphenylsulfonium trifluoromethanesulfonate,
4-tert-butylphenyldiphenylsulfonium trifluoromethanesulfonate,
4-phenylthiophenyldiphenylsulfonium hexafluorophosphate,
4-phenylthiophenyldiphenylsulfonium hexafluoroantimonate,
1-(2-naphtholylmethyl)thiolanium hexafluoroantimonate,
1-(2-naphtholylmethyl)thiolanium trifluoromethanesulfonate,
4-hydroxy-1-naphthyldimethylsulfonium hexafluoroantimonate,
4-hydroxy-1-naphthyldimethylsulfonium trifluoromethanesulfonate,
cyclohexylmethyl(2-oxocyclohexyl)sulfonium trifluoromethanesulfonate,
cyclohexylmethyl(2-oxocyclohexyl)sulfonium perfluorobutanesulfonate,
cyclohexylmethyl(2-oxycyclohexyl)sulfonium perfluorootcanesulfonate,
2-methyl-4,6-bis(trichloromethyl)-1,3,5-triazine,
2,4,6-tris(trichloromethyl)-1,3,5-triazine
2-phenyl-4,6-bis(trichloromethyl)-1,3,5-triazine,
2-(4-chlorophenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine,
2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine,
2-(4-methoxy-1-naphthyl)-4,6-bis(trichloromethyl)-1,3,5-triazine,
2-(benzo[d][1,3]dioxolan-5-yl)-4,6-bis(trichloromethyl)-1,3,5-triazine,
2-(4-methoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine,
2-(3,4,5-trimethoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine,
2-(3,4-dimethoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine,
2-(2,4-dimethoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine,
2-(2-methoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine,
2-(4-butoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine,
2-(4-pentyloxystyryl)-4,6-bis(trichloromethyl)-1,3, 5-triazine,
diphenyl disulfone,
di-p-tolyl disulfone
bis(phenylsulfonyl)diazomethane,
bis(4-chlorophenylsulfonyl)diazomethane,
bis(p-tolylsulfonyl)diazomethane,
bis(4-tert-butylphenylsulfonyl)diazomethane,
bis(2,4-xylylsulfonyl)diazomethane,
bis(cyclohexylsulfonyl)diazomethane,
(benzoyl)(phenylsulfonyl)diazomethane,
1-benzoyl-1-phenylmethyl p-toluenesulfonate (generally called benzoin tosylate),
2-benzoyl-2-hydroxy-2-phenylethyl p-toluenesulfonate (generally called xcex1-methylolbenzoin tosylate),
1,2,3-benzenetolyl trismethanesulfonate,
2,6-dinitrobenzyl p-toluenesulfonate,
2-nitrobenzyl p-toluenesulfonate,
4-nitrobenzyl p-toluenesulfonate,
N-(phenylsulfonyloxy)succinimide,
N-(trifluoromethylsulfonyloxy)succinimide,
N-(trifluoromethylsulfonyloxy)phthalimide,
N-(trifluoromethylsulfonyloxy)-5-norbornene-2,3-dicarboxyimide,
N-(trifluoromethylsulfonyloxy)naphthalimide,
N-(10-camphorsulfonyloxy)naphthalimide and the like.
The chemical amplification type positive resist composition [3] of the present invention can improve deterioration in abilities due to deactivation of an acid following leaving after exposure, by adding as a quencher a basic nitrogen-containing organic compound, such as amines. Specific examples of the basic nitrogen-containing organic compound used as a quencher include compounds of the following formulae. 
In the above formulae, R4, R5 and R10 represent each independently hydrogen, alkyl, cycloalkyl or aryl. The alkyl, cycloalkyl or aryl may be each independently substituted with, a hydroxyl group, amino group or alkoxy group having 1 to 6 carbon atoms. This amino group may be substituted with an alkyl group having 1 to 4 carbon atoms. This alkyl preferably has about 1 to 6 carbon atoms, this cycloalkyl preferably has about 5 to 10 carbon atoms, and this aryl preferably has about 6 to 10 carbon atoms.
R6, R7 and R8 represent each independently hydrogen, alkyl, cycloalkyl, aryl or alkoxy. The alkyl, cycloalkyl, aryl or alkoxy may be each independently substituted with a hydroxyl group, amino group or alkoxy group having 1 to 6 carbon atoms. This amino group may be substituted with an alkyl group having 1 to 4 carbon atoms. This alkyl preferably has about 1 to 6 carbon atoms, this cycloalkyl preferably has about 5 to 10 carbon atoms, this aryl preferably has about 6 to 10 carbon atoms, and this alkoxy preferably has about 1 to 6 carbon atoms.
R9 represents alkyl or cycloalkyl. The alkyl or cycloalkyl may be each independently substituted with a hydroxyl group, amino group or alkoxy group having 1 to 6 carbon atoms. This amino group may be substituted with an alkyl group having 1 to 4 carbon atoms. This alkyl preferably has about 1 to 6 carbon atoms, and this cycloalkyl preferably has about 5 to 10 carbon atoms.
A represents alkylene, carbonyl, imino, sulfide or disulfide. The alkylene preferably has about 2 to 6 carbon atoms.
R4 to R10 may have any of a linear structure and a branched structure providing they can take both structures.
Specific examples of such compounds include hexylamine, heptylamine, octylamine, nonylamine, decylamine, aniline, 2-, 3- or 4-methyaniline, 4-nitroaniline, 1- or 2-naphthylamine, ethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4xe2x80x2-diamino-1,2-diphenylethane, 4,4xe2x80x2-diamino-3,3xe2x80x2-dimethyldiphenylmethane, 4,4xe2x80x2-diamino-3,3xe2x80x2-diethyldiphenylmethane, dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, N-methylaniline, piperidine, diphenylamine, triethylamine, trimethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, triheptylamine, trioctylamine, trinonylamine, tridecylamine, methyldibutylamine, methyldipentylamine, methyldihexylamine, methyldicyclohexylamine, methyldiheptylamine, methyldioctylamine, methyldinonylamine, methyldidecylamine, ethyldibutylamine, ethyldipentylamine, ethyldihexylamine, ethyldiheptylamine, ethyldioctylamine, ethyldinonylamine, ethyldidecylamine, dicyclohexylmethylamine, tris[2-(2-methoxyethoxy)ethyl]amine, triisopropanolamine, N,N-dimethylaniline, 2,6-isopropylaniline, imidazole, pyridine, 4-methylpyridine, 4-methylimidazole, bipyridine, 2,2xe2x80x2-dipyridylamine, di-2-pyridylketone, 1,2-di(2-pyridyl)ethane, 1,2-di(4-pyridyl)ethane, 1,3-di(4-pyridyl)propane, 1,2-bis(2-pyridyl)ethylene, 1,2-bis(4-pyridyl)ethylene, 1,2-bis(4-pyridyloxy)ethane, 4,4xe2x80x2-dipyridyl sulfide, 4,4xe2x80x2-dipyridyl disulfide, 1,2-bis(4-pyridyl)ethylene, 2,2xe2x80x2-dipicolylamine, 3,3xe2x80x2-dipicolylamine, tetramethylammonium hydroxide, tetraisopropylammonium hydroxide, tetrabutylammonium hydroxide and the like.
It is preferable that the chemical amplification type positive resist composition of the present invention contains an acid generating agent in an amount of 0.3 to 30 parts by weight, and a compound of the formula (I) in an amount of 0.2 to 50 parts by weight, more preferably of 0.5 to 20 parts by weight based on 100 parts by weight of a resin insoluble or poorly soluble itself in an alkali but becoming soluble in an alkali by the action of an acid, in the composition.
When a basic compound is used as a quencher, it is preferable that the composition of the present invention contains the basic compound in an amount of 0.001 to 5 parts by weight, 1 more preferably 0.01 to 1 part by weight based on 100 parts by weight of the above-mentioned resin in the resist composition.
The composition of the present invention can also contain a small amount of various additives such as sensitizers, solution suppressing agents, other resins, surfactants, stabilizers, dyes and the like, if necessary.
The resist composition of the present invention is usually used as a liquid containing the above-mentioned components dissolved in a solvent, and the liquid is applied on a substrate such as a silicon wafer and the like according to an ordinary method such as spin coating and the like.
Any solvents may be used here providing they dissolve each component, show suitable drying speed, and give a uniform and smooth film after evaporation of a solvent. Solvents generally used in this field can be used as the solvent. Examples thereof include glycol ether esters such as ethylcellosolve acetate, methylcellosolve acetate or propylene glycolmonomethyl ether acetate; esters such as ethyl lactate, butyl acetate, amyl acetate or ethyl pyruvate; ketones such as acetone, methyl isobutyl ketone, 2-heptanone or cylohexanone; and cyclic esters such as xcex3-butyrolactone; and the like. These solvents can be used each alone or in combination of two or more.
On a resist film applied on a substrate and dried, exposure treatment for patterning is performed, then, heating treatment for promoting a protective group-removing reaction is conducted. Thereafter, the resist film is developed with an alkali developer. The alkali developer used here can be selected from various alkaline aqueous solutions used in this field, and generally, often used are aqueous solutions of tetramethylammonium hydroxide and (2-hydroxyethyl)trimethylammonium hydroxide.
The following examples will illustrate the present invention further specifically, but do not limit the scope of the present invention at all. In examples, % and parts representing content or use amount are by weight unless otherwise stated. The weight-average molecular weight (Mw) and polydispersion (Mw/Mn) were measured by gel permeation chromatography using polystyrene as a standard.